This invention relates to a fan blade in solid material for a gas-turbine engine.
The fan blades are the foremost rotating components of a gas-turbine engine. Besides the inflowing air, these blades are exposed to ingested foreign bodies, such as birds, primarily in the take-off phase. In order to withstand the extremely high loads, in the event of a bird strike for example, the fan blades, which are made of a solid high strength-material, such as titanium or a corresponding alloy for example, must be dimensioned adequately. The high weight resulting therefrom significantly increases the costs of these blades and entails high mechanical loads arising from the natural vibrations and the vibration amplitude as well as the centrifugal forces. Furthermore, the fan protective casings, or fan containments, must be designed in correspondence with the weight of the fan blades. This involves a further increase in weight and additional costs.
For high-power aircraft engines, fan blades with closed, inner cavities have already been proposed to reduce the weight and to avoid the disadvantages resulting from too high a mass. The methods for the production of such hollow blades described, for example, in U.S. Pat. No. 6,033,186 and U.S. Pat. No. 5,692,881 are, however, very costly. Particularly with small and medium-power engines, the high costs for such hollow fan blades are not effective in relation to the weight saving obtained and the advantages resulting from such a weight saving.